mirror of
https://github.com/ruby/ruby.git
synced 2022-11-09 12:17:21 -05:00
51 lines
870 B
Ruby
51 lines
870 B
Ruby
|
# The Computer Language Shootout
|
||
|
|
# http://shootout.alioth.debian.org/
|
||
|
|
# Contributed by Sokolov Yura
|
||
|
|
|
||
|
|
def eval_A(i,j)
|
||
|
|
return 1.0/((i+j)*(i+j+1)/2+i+1)
|
||
|
|
end
|
||
|
|
|
||
|
|
def eval_A_times_u(u)
|
||
|
|
v, i = nil, nil
|
||
|
|
(0..u.length-1).collect { |i|
|
||
|
|
v = 0
|
||
|
|
for j in 0..u.length-1
|
||
|
|
v += eval_A(i,j)*u[j]
|
||
|
|
end
|
||
|
|
v
|
||
|
|
}
|
||
|
|
end
|
||
|
|
|
||
|
|
def eval_At_times_u(u)
|
||
|
|
v, i = nil, nil
|
||
|
|
(0..u.length-1).collect{|i|
|
||
|
|
v = 0
|
||
|
|
for j in 0..u.length-1
|
||
|
|
v += eval_A(j,i)*u[j]
|
||
|
|
end
|
||
|
|
v
|
||
|
|
}
|
||
|
|
end
|
||
|
|
|
||
|
|
def eval_AtA_times_u(u)
|
||
|
|
return eval_At_times_u(eval_A_times_u(u))
|
||
|
|
end
|
||
|
|
|
||
|
|
n = 500 # ARGV[0].to_i
|
||
|
|
|
||
|
|
u=[1]*n
|
||
|
|
for i in 1..10
|
||
|
|
v=eval_AtA_times_u(u)
|
||
|
|
u=eval_AtA_times_u(v)
|
||
|
|
end
|
||
|
|
vBv=0
|
||
|
|
vv=0
|
||
|
|
for i in 0..n-1
|
||
|
|
vBv += u[i]*v[i]
|
||
|
|
vv += v[i]*v[i]
|
||
|
|
end
|
||
|
|
|
||
|
|
str = "%0.9f" % (Math.sqrt(vBv/vv)), "\n"
|
||
|
|
# print str
|